Direct-current track-circuit for railway signals



s. s. sToLP DIRECT CURRENT. TRACK CIRCUIT FOR RAILWAY $IGNALS Filed Feb. 24, 1920,

Samuel #5: 1512250 'sA viUiiL s. s'roLr, or cnroAG Patented May 3, 1927.

stares teasers o, ILLInois, assienon 'ro onnntns IB. crimson, or

enroneo, rumors, Q

DIREGT-QURREIYT 'TRACK-CIRGUIT FOR RAILWAY SIGNALS.

Application filed February '24, 192 1). Serial No. 360,613. I

The invention relates to railway signals and particularly to the so-called track circuit comprismg a'source of direct current,

the rails of the'track in a given section or block and the-track relay by whichthe operation of the corresponding signal mechanismiscontrolled. The invention is more especially applicable to those track circuits vin which primary cells or a storage battery, having low internal resistance, is v asthe source otcurrent.

employed TVhile external resistance is commonly employcd tolimit the outflow ot current from the'battery the amounto'f this limiting resistance is usually constant and it is in cir- 'cuit at'all times. It follows that the greatest li-mitingresistance which can be used is therefore only that which will permit the "greatest current flow required at any time. Many track circuits now in'use accordingly present the anomalous condition that the consumption of battery current during all of the time that thetrack is unoccupied is equal to that-which is'only momentarily required at the instant the train shunt is removed'and many times this'amount of currentis used when the track'is occupied and no work is being done. The track battery "accordingly requires renewal. much more t'requently than should be necessary and the delay-of a; train within the block may so exhaust the battery that the signal will fail tooperate when traliic is again restored.

Obviously an ideal condition would be one in which an abundance ot current is momentaril sn 7 Dlie'd for thepick u i of the track relay 'whenthe train moves out of the blockwith' only the minimum amount of our- 1 rent necessary to prevent release or the relay furnished duringithe remainder of the time that the track is unoccupied and no current i at all supplied when the train is in the block.

()n the other hand, there will be no premature exhaustion of the battery by delayed trains if the amount of current supplied when thetrack is occupied is not greatly in excess of-that supplied when the track is unoccupied and it is believed tobe impracticable to completely open circuit the battery at any time.

The object of the present invention is to provide an-improved track circuit in'w'hioh the tore goingtlesirable condition is substanduring the remainder of the'time when the I track is unoccupied in allcases where the condltion of the ballast Wlll permit iand the introduction of ASlllll larger limiting resist ance when'the train shunt has been applied.

Increased safety and a greater certainty of signal operation are thereb bothobtained in addition to economy of battery current. A- feature of the invention also provides for the momentary use of a supplemental batever increased voltage is desirable for accomplishing pick up of the track relay,

The accompanying drawing "is a conven tional representation of one form proved track circuit. 7 a

The insulated rails of a single section of track are indicated at 10 and 11. The track of the imv 'tery inseries with. the track'battery whenrelay is represented at 12,the relay leads 7 being shown at 13 and 14, The train shunt is represented at 15 and the ballast shunt at 16. These parts are all usual in direct current track circuits except that when desired the length of the circuit may be greater than has heretofore been customary.

The track battery comprising three pri mary cells oi. low internalresistanco con- 'nected in multiple is indicated at 1?, When a supplemental battery is used it may be located as shown at 18. This supplemental battery may consist of a single cell of like "low internal resistance. with each cell of battery 17. {The supplementary battery 18 is employedonly momentarily tor the pick up of track relay 12 and is then'connected in series with battery 17 In the arrangement illustrated other times. 7

One side of track battery 17- is perma-' nently connected :to rail 11 through battery 17 is connected to rail 10.3through limiting resistance 20, control relay 21 andlead 22.

it'is onopen circuit at all ice lead 19. The other side otthe track battery Also, when-the track isunOccupied, there is a shunt path for current around relay 21 comprising lead 23, connected to the remote v back contact 25 of relay 21 and lead 26, the

v sp'ect 'to theresistance of relay 21.

latter extending from the armature 27 of relay 21 to lead 22. The normal battery hm iting resistance when the track is unoccupied is thus limiting resistance 20 plus the effective resistance of relay 21 and supplemental limiting resistance 24 in parallel, plus theresistance of leads 19 and 22. Furthermore, the proportion of current passing through the control relay 21 is determined 7 by the adjustment of resistance 24 with re- In the arrangen-ient shown the drawing the current passes through relay 21 when the track is unoccupied, but not in suflicient strength to cause-thisrelay to pick up, first because relay 21 isjoined parallel with resistance 24 and second, because the total current strength is reduced by the resistance of the track relay 1,2.

.VVhe-n the train shunt 15 is applied, control relay '21 picks up, and back control 25 being opened, all of the current passes through relay 21. The picking up of relay 21 when the train shunt 1-5 enters the block is 'due'to the fact that the short circuiting of the resistance of track relay 12 increases the total current strength to such an amount that the part passing through relay 21 is greater than the pickup constant of this relay. The battery limiting resistance is thus increased and becomes limiting resistance-20 plus the resistance {of relay 21 and leads 19 =and22. It should be observed that just as soon as relay armature 27 has been lifted clear of its back contact 25, all of the current must pass through relay 21 and complete pick up of this relay is insured. Should track relay 1-2 have failed to drop from the application of the train shunt l5 alone, it will certainly be released by the pick up of control relay 21 due to the increased "battery limitingresistance thereby inserted. v

A second relay 28, shown as having two front contacts 33 and 34, is also usedat the battery end of the circuit. This relay is preferably constructed for retarded release,

as by being formed with a copper sleeve 29 on thecore. As shown, the relay 2 8 is on open circuit when the track .is unoccupied.

Upon the application of the train shunt, as

15, relay 28 isbrid-ged across the track, as by being connected by lead 30 tobattery lead 19 at one side, and by lead 31, front contact 32-of relay 21 and lead 26 to ;lead 22 at the other side. The addition of this shunt across the track promotes safety and it also draws more current through relay 21 for holding thesame, thus providing-a safeguard against any accidental release of relay 21 while the train shunt, as-l5, is applied. It is the intention thatrelay 28Lshal'l receive a pick up current only upon removal of the train shunt, as 15.

When relay 28 picks up, the closing of ts front contact 33 provides a direct path for current across the terminals of relay 21 whereby relay 21 releases. This in turn puts relay 28 again on open circuit, due to the opening of front contact 32 of relay 21, but delayed release of relay 28 does not permit the opening of either of its front contacts 33 or 34 until pick up of the track relay 12 has been accomplished. As shown,the closing of front contact 33 of relay 28' bridges the terminals of relay '21 through a wire" 35,

which connects one of the'arms, as '36-, of the armature of relay 28 with lead 23, an da wire is a direct path for current from suippiemental battery 18 to lead 22 through lead 40, front contact 34, armature arm 38,- wires '39, 35, armature arm 36, front'contact -and wire 37 age with no limiting resistance is thus momentarily Supplied to the track foraccorfl plishing pick up ,of the track relay 12. ,If supplemental battery 18 were omitted, then Battery current of increased velt the full current strength of track battery. 17 7 alone would be momentarily applied to the track without limiting resistance. many cases this would be suflicient.

It'will be observed that when front contacts 33 and 34 of relay 128 are closed, lead 23 and battery limitingresistance20' afford.

an alternate path for current around the supplemental battery 18. Owing to the low internal resistance of battery 18,- this-alternate path for cur-rent hasbut little effect in reducing the voltage obtained by connecting batteries 17 and 18 in series.

suitable adjustment of these contacts in a well known manner, forwith front contact 33 open and front contact 34 closed, acu-rrent impulse having the combined voltage of batteries 17 and 18 would be applied to relay 21.

If relay 28 should fail to pick up" on removal of the train shunt, relay .21 would never release for, when its back contact '25 has been opened,- there is no alternate path for current to the track and all of the current passes through the said relay :21. A-ccidental release of relay 21 before pick up of relay 28 has been accomplished is thereby prevented. I

Except when the ballast shnntil-fi is .so favorable that the track relay .12 can receive a pick up current from battery .17

equal to limiting resistance 20 plus the reslstance of relay 21, the operativeness of the circuit to clear the signal upon removal relay 28 may, without danger, lbe made of low resistance as compared'with the resistance of the track relay 12 and ballast shunt 16 and such a construction of the relay is preferred.

When relay 28'is of the said low resistance, it receives the major part of the current as soon as the train shunt is removed and the circuit is operative until ballast becomes so unfavorable that pick up of the track relay 12 would be useless because of insuflicient current for holding. On the other hand, if'desired, relay 28 may be constructed with opposed windings of like resistance, one of which (not shown) is connected across the battery 17 when relay 21 picks up while the other winding is connectedv across the track in the manner represented for the single winding shown in the drawing. When the train. shunt, as 15, is applied the two windings receive nearly equal amounts of currents and counter balance each other. When the train shunt is removed, the effective resistance of the ballimiting resistance and relay from the battery, as shown.

The following tables of assumptions and calculations of results by Ohms law are given for the purpose of illustrating the operativeness of a circuit arranged in accordance with the drawing.

Table: of assumptions.

Circuit length=2500 feet.

Combined resistance of rails 10, 11:0.25

ohm. I

Resistance of battery leads 19, 22,:0.06

ohm.

Resistance of relay leads 13, 14,:010

ohm. I

Release constant of track relay 12 .037

amp. V

- Battery 17:0.65 volts.

Battery 18:0.65 volts.

Limiting resistance 20 1 ohm Limiting resistance 24 1 ohm 1.5 ohm.

Resistance of relay 21 1 ohm Pick up constant of relay 21:.150 amp.

Resistance of relay 28:1 ohm. i I

Pick up constant of relay 28:.125 amp.

Resistance, of poorest ohm.

Table of calarwlateclresults.

Current relay 21 when track isluno'ccupied:.093 amp.

Initial pick up current. relay 21' when train shunt15' is applied at relay end of track:.175'amp.

Follow up current relay 21 when train train shunt: .06

shunt 15 is applied and back contact 25 of relay 21 has been opened:.275 amp. f

Holding current relay 21 when train shunt'has been applied and front contact I 32 of relay 21 is closed:.288 amp. 7

Current relay 28 when train shunt 15 is applied at relay end of track=fl076 amp.

Pick .up current supplied to relay 28 when train shunt is removed (average ballast)=.175 amp. 7 V

Minimumresistance of ballast shunt 16 over which pick up current equal to pick up constant of relay 28 upon removal oftrain shunt:O.65 ohm. j p

Holding current supplied to rack relay 12 when track is unoccupied (average ballast):.080 amp. Pick up current momentarily supplied to track'relay 12 upon'removal of train shunt (average ballast):.280 amp.

Total current consumption track unoccupied:.186 amp.

Total current consumption track occupie'd:.316 amp.

, GLII'IBlllZfliliIliSllGd by the supplemental battery. 18; does not appearin the figures givenxfor total current consumption -for the tarily in circuit and its deterioration is negligible.

I claim as my invention:

1. The method of operating a closed track circuit having a battery limiting reslstance which consists in increasing the battery limiting resistance when the train shunt is applied and momentarily closing a shunt around the battery limiting resistance upon removal of the train shunt. V w

2. The method of accomplishing pick up of the track relay in a closed track circult,

reason that this battery is only momenhaving a track batterv which consists in 1110- mentarily connecting another battery 111 series with. the track battery. v; r v

3. The method of accomplishing pick up of the track relay in a closed track circuit mentarily connecting another battery in se rice with the track battery without opening the track circui l. The method of accomplishing pick up of the track relay in a closed track circuit having a track battery and battery limiting resistance which consists in momentarily closing a shunt around the battery limiting resistance and at the same time. connecting another battery in series with the track battery. V

5. The method of operating a closed track circuit having a track battery and battery limiting resistance whichconsists in increasing the battery limiting resistance when the train shunt is applied and momentarilyclosing a shunt around the battery limiting resistance upon removal of the train shunt and at the same time connectinganother battery in series with the track battery.

6. The method of operating a closed track circuit having a track battery and a normal battery limiting resistance which consists in introducing an additional battery limiting resistance when the train shunt is applied and momentarily closingashunt around both the said normal and additional battery limiting resistance upon removal of the train shunt. 7. The method of operatingv a closed track circuit having a track battery and a normal battery limiting resistance which consists in introduclng an additional battery llmiting resistance when the train shunt is applied and momentarily closing a shunt around both the said normal and additional battery limiting resistances upon removal of thetrain shunt, and at the'same time connecting another battery in series with the track battery.

8. The method of operating a closed track circuit having a track battery and a normal battery limiting resistance which consists in introducing an additional battery limiting resistance when the train shunt is applied and momentarily closing a shunt around both the said normal and additional battery limiting resistances upon removal of the train shunt, and at the same time connecting another battery in series with the track batrailsfrom a current source of predetermined voltage after pick up of the relay has been accomplished and n'iomentarily supplying current to the track rails from a current source of higher voltage for, the'piclr up. 7 11. The unethod of operating a closed track circuithaving a track battery and a battery limiting resistance which consists in momentarily closing a shunt including an additional battery around the battery limiting resistance upon removal of the train shunt.

12. The method of operating a closed track circuit having a track battery and battery limiting resistance which consists in increasing the battery limiting resistance when the train shunt is applied and moine i tarily closing ,a shunt including anadditional battery around the battery limiting re sistance upon removal of the train shunt.

13. The method Ora-voiding excessive consumption of battery current during thelapplication otthe train shuntto-a closed track circuit having battery limiting resistance di vided into two parts arranged in parallel ln'anchesof the circuit which, consists in opening I1eottlie said'parallel branches of the circuit fwhen the said train shunt is applied.

14. The combination with a' closed track circuit comprising the rails of the track, a track battery, a track relay anda battery limiting resistance, of a normally open.

shunt around the battery limiting resistance, a supplemental battery in said shunt and means for closing the said shunti:

15. The combination. with a -closed track circuit comprising the rails of the track, a

of predetermined resistance around the con- .trol relay opening at its said had; contact.

17 The combination with a closed track circuit comprising the rails o -t the track, a track relay, a track battery and a control relay between the battery-and track, of back and front contacts forthe said control relay,

the control relay opening at its said back contact and a shunt of predetermined resistance across the rails of the track opening at the front contact of the control relay.

18. The combination with a closed track circuit comprising the rails of the track, a track relay, a track battery and, a; control relay between the battery and track, of a back contact for the control relay, a shunt of a shunt of predetermined resistance around iltldOW. resistance shunt. l 9. The combination with a closed track circuit comprising the rails of the track, a

track relay, a track battery and two battery lin ting resistances arranged in parallel branches of the circuit, of, means for opening one oftthe-said circuit branches,- a normally open low. resistance shunt around both the said branches of the circuit, and

means for ,closing the said low resistance shunt 20. The combination with a closed track circuit con'iprisingthe rails of the track, a track relay,a track battery and two battery limi g resistances arranged. in parallel branches .of the circuit, of means for opening one of the said circuitbranches, a nor niaily open low resistance shunt around both of the saidbranches of the circuit, a sup plemental batte ry' in said low resistance sl'mnhand meansforclosing the said low resistance shunt.

21. The combination with a closed track circuit comprising the rails of the-track, a track relay, a track battery and a control relay between the battery and track, of a front contact for the said control relay, a shuntacross the track opening at the front contact of the control relay, a second relay in s 'l shunt, a front contact for the last mentioned relay and a low resistance shunt around the control relay opening at the said front contact of the other relay.

The combination with a closed track circuit comprising the rails of the track, a track relay, a track. battery and a control relay between tiie battery and track, of a front contact for the said control relay, a shunt across the track opening at the front contact of the control relay, a retarded release relay in-said shunt,a front contact for the retarded release relay and a low resistance shunt around the control relay, opening at the said front contact of the retarded release relay.

23. The combination with a closed track circuit comprising the rails of the track, a

track relay, a track battery and a control relay between the battery and track, offrontand back contacts 'forthe control relay, a shunt of predetermined resistance around the control relay opening at the back contact of the control relay, a shunt across the track opening at the front contact of the control relay, a second relay in the last mentioned shunt, a front contact for the last mentioned relay, and a low resistance shunt around the control relay and the said first mentioned shunt opening at the front contact of the said second relay.

l control relay, and means for closing;

The combination with a closed track circuit compri track openinoat the front contact of the.

c onirol relay, a retarded release relay in the last mentioned shunt, a front cont for the retarded release relay, and a low resistance shunt around the control relay and the I. tmentioned shunt opening at the front contact of the retarded release relay.

25.-The combination with a closed track circuit comprising the rails ofthe track, a track relay, a track battery and an external battery limiting resistance and a control relay located in the circuit between the battery and track, of a front contact for the control relay, a shunt across the track openmg at the front contact of the control relay, a second relay in said shunt, two front contacts. for the last mentioned relay, a low resistance shunt around the control relay openingat one of the front contacts of the second mentioned relay, ashunt around the said external battery limiting resistance and the control relay opening at the other front contact of the second mentioned relay and a sfipplemental battery in the last mentioned s unt.

26. The combination with a closed track circuit comprising the rails of the track, a track relay, a track battery and an external battery limiting resistance and a control relay located in the circuit between the battery and track, of a front contact forthe control relay, a shunt across the track opening at the front contact-of the controlrelay, a retarded release relay in said shunt, two front contacts for the retardedrelease relay, a

low resistance shunt around the control relay a opening at one of the front contacts of the retarded release relay, a shunt around the said external battery limiting resistance and the control relay opening at the otherfront contact of the retarded releaserelay and a sfipplemental battery in the last mentioned s unt.

27. The combination with a closed track circuitcomprising the rails of the track, a

shunt, two front contacts for the last men-' tioned relay, alow resistance shunt around the control relay opening at one of thefront contacts of the second mentioned relay, a

circuit comprising the rails of the track; a

track relay, a track battery and an external battery limiting resistance and a control relay located in the circuit between the battery and track. of front and back contacts for the control relay, a shunt of predetermined resistance around the control relay opening at its back contact, a shunt across the track opening at the front contact of the control relay, a retarded release relay in the last mentioned shunt, two front contacts for the retarded release relay, a low resistance shunt around the control relay opening at one of the front contacts of the retarded release relayy a shunt around the said external battery lin'iiting resistance and the control relay opening at the other front contact of the retarded release relay and a supplemental bat tery in the last mentioned shunt.

29. The method of accomplishing pick up of the track relay in a closed track circuit having a track battery and a battery li1niting resistance Without opening'the circuit,

which consists in connecting another bat-tery.

in series with the track battery and in shunt With the said limiting resistance.

30. The method of operating a closed track circuit'having a battery limiting resistance which consists in increasing the battery limiting resistance when the train shunt is applied and momentarily decreasing the ing ashunt around the battery limiting resistance upon removal of the train shun-t.

SAMUEL S. STOLP.

CERTIFICATE OF CORREGTEON.

Patent No. 1,626,643. Granted May 3, 1927, to

SAMUEL S. STOLP.

it is hereby certified that the above numbered patent was erroneously issued to Charles B. Gillson as assignee of the entire interest in said invention whereas said Letters Patent should have been issued to the inventor, said "Stolp" and Charles B. Gillson, said Gillson being assigneeof one-half interest only in said invention, as shown by the records of assignments in this office; and that the said Letters Patent should be read with thiscorreotion therein that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 14th day of June, A. D. 1927.

' M. J. Moore,

Sell. Acting Commissioner of Patents. 

